ISOLATION AND CHARACTERIZATION OF INFLUENZA-A VIRUSES FROM AVIAN SPECIES IN HONG-KONG

Abstract

Surveillance of apparently healthy ducks, chickens and geese at a poultry dressing plant in Hong Kong yielded 51 hemagglutinating viruses, 25 of which were influenza A viruses. Of these, 24 were subtyped into 13 combinations based on hemagglutinin and neuraminidase surface antigens. Of the 13 different influenza A viruses isolated, 7 possessed combinations of hemagglutinin and neuraminidase subunits that were not reported previously, i.e., Hav2N1, Hav2Nav5, Hav4N2, Hav7N2, Hav7Nav1, Hav7Nav3 and Hav7Nav6. Four of the isolates were non-avid: they were not neutralized by antisera to any of the reference subtypes of influenza A viruses, yet antisera to each isolate inhibited both that virus and a known reference strain. The large number of combinations of hemagglutinin and neuraminidase and the isolation of 2 different influenza A viruses from 1 duck suggests that recombination may be occurring in nature.